Leading figures on the Tory right say they are "on manoeuvres" in an attempt to put pressure on David Cameron to repatriate powers at the EU summit, which opens in Brussels on Thursday evening.

Edward Leigh, the veteran rightwinger, convened a meeting of the three main groups on the right – the No Turning Back Group, the 92 Group and the Cornerstone Group – to make sure Cameron returns home with "clear gains".

The scale of the challenge to the prime minister was underlined when Owen Paterson, the Northern Ireland secretary, suggested on Wednesday that a revision of the Lisbon treaty to underpin tough new fiscal rules for the eurozone should be put to the British people in a referendum.

Paterson's intervention, which came three days after a similar intervention by his patron Iain Duncan Smith, runs directly counter to government policy which was put on a statutory footing last July in the European Union Act. This holds that a referendum will only be held if significant UK powers are transferred to the EU.

As No 10 sources indicated that Paterson had been spoken to in strong terms, Boris Johnson upped the ante by echoing his call for a referendum. "It's absolutely clear to me that if there is a new treaty at 27 – if there is a new EU treaty that creates a kind of fiscal union within the eurozone – then we would have absolutely no choice either to veto it or to put it to a referendum," the London mayor told the BBC.

Senior figures on the Eurosceptic right said that the interventions by Duncan Smith and Paterson were part of a co-ordinated effort by the right to put pressure on Cameron. One senior figure said: "It is no accident what Owen said. We are on manoeuvres. This is co-ordinated. We are putting pressure on the PM on the EU."

The right have two main aims, first to put pressure on the prime minister to accept the calls by Paterson, Duncan Smith and Johnson that a referendum should be held on such a momentous EU treaty change even if it just applies to the 17 eurozone countries. Some Eurosceptic MPs are also examining plans for what is being dubbed a two-stage "sandwich referendum". A first referendum would be held on the findings of a white paper setting out the British position on repatriating powers to Britain. If negotiations in the EU on this failed then a second referendum would be held which would effectively be a vote on Britain's membership of the EU.

Others on the right are pushing a second aim of demanding an immediate repatriation of powers at the summit. One MP said: "This is designed to ensure that the prime minister comes back from Brussels with clear gains. He can't just say that at some point in the future they have agreed to look at balance of powers. We need repatriation of powers, possibly social and employment or fisheries. It has to happen."

The Eurosceptics hailed an intervention by Chris Grayling, Duncan Smith's deputy at the department of work and pensions. In a review of Cameron's appearance at prime minister's questions on the BBC Daily Politics programme, Grayling said: "He gave a very clear message not simply about safeguarding the financial services industry but about his intent to bring back to the House of Commons powers of regulation over what is one of our crucial industries. That is a clear statement of intent."

One Eurosceptic said: "Chris deliberately misinterpreted what the prime minister said. Chris said he had said he would repatriate powers. Cameron did not say that."

Tory MPs will voice their concerns in a debate in Westminster Hall convened by Bernard Jenkin, a Duncan Smith ally. In a Guardian article, Jenkin endorses the call for a referendum, adding: "If we are not prepared to press to change in our terms of membership now, then when will we ever? This really is the EU endgame."